Thermostatic control device



Jan. 12 1926. 1,569,312

c. F. H. BOHNHRDT THERMSTATIC CONTROL DEVLCB Filed July 7, 1925 VIIIIIIH Patented Jan. 12, 1926.

UNITED STATES PATENT oFFicE.

CHARLES I?. H. BOI-INIIARDT, 0F BALTIIvIOIR/E, MARYLAND, ASSIGNOR TGHARRY D.

HARVEY, OF BALTIMORE, MARYLAND. v

THERMOSTATIC CONTROL DEVICE.

Application led July 7,

To aZZfwZLom t may concern:

Be it known that I, CHARLES F. H. BoHNi-mnnr, a citizen of the UnitedStates, residing at Baltimore, in the State of Maryland, have inventedcertain new and useful Improvements in Thermostatic Control Devices, ofwhich the following is a specification.

This invention relates to thermostatic control devices for controllingthe flow of gas to metal melting furnaces, so as to cut down or stopthegas flow when the metal is heated to the desired temperature.

In carrying out therinvention, I provide an outer casing or shell ofsubstantially cylindrical form, open at the top and closed at thebottom, and having in its side wall inlet and outlet openings arrangedone above the others As the gas may How in either direction through thedevice, either Aopening may be considered the inlet or outlet opening.Within this casing I arrange a removable drum which closes the top ofthe casing, and the lower wall of the drum forms a partition in thecasing between the inlet and outlet openings. The drum is provided withopenings in its side walls to establish communication between one of theopenings in the casing and the interior Yof the drum, Vand an adjustablevalve cylin der extends transversely through the drum and is providedwith ports for permitting the gas to flow from the interior of the drumthrough the valve casing and intothe space or compartment below thedrum, and thence through one of the openings in the casing to theburners of the furnace. The valve is movable in this valve casing by rasystem of multiplying levers, all of which .are supported on a bracketdepending from the lower side of the drum. Thus, the drinn, valve andlevers are all associated together as a unit which may be readily placedin or removed from the casing.

. lVhen placed within the casing, oner of these levers rests upon amember in the bottom of the casing'which is actuated by an eX- pansiondevice which extends into the molten metal. As the temperature of themetal rises, the expansion device moves downward, allowing the levers tomove under the weight of the valve and the latter gradually closes theports and cuts off' the How of gas. In order to provide a small flow ofgas to keep the .burners lighted, after sembling and cheapens the costof manufacn ture.

In the accompanying drawing,

Fig. l is a side elevation of the manometer;

Fig. 2 is a top plan view of the same;

Fig. 3 is a central section on the line 3--3 of Fig. 2;

Fig. l is a side elevation of the drum; and,

Fig. 5 is a plan view of the' piston valve.

Referring to the drawing, .a represents the outer casing or shell of themanometer comprising a substantially cylindrical side wall l and abottom wall 2. This casing has in its upper portion, an inlet opening 3,and in its lower portion an outlet opening 4. A drum b fits into theupper portion of the casing and the wall 5 of the drum has flanges whichproject over the side wall of the casing. Screws 6, passing through saidflanges, secure the drum andcasing together. The lower wall 7 of thedrum eX- tends across the central portion of the casing and forms apartition which separates Athe inlet opening 3 from the outlet opening4. The side wall of the drum lits snugly withinthe casing at the top andbottom of said wall, but the intermediate portion of the drum is spacedfrom the side wall to form an annular channel 8, between the drum andcasing. y This intermediate portion of the side wall of the drum isprovided with a plurality of ports 9, through `which gas may flow fromthe channel S,

which latter channel is connected with the inlet port 3. The upper headof the drum is formed with a cylindrical opening l() and the lower head7 of the drum provided with an opening ll of smaller diameter than theopening l0 and in axial alinement therewith. A cap 12 closesv theopening 10 and has a cylindrical portion 13 which forms a guide for acylindrical valve casing 14C, which casing extends through the drum andinto the opening 11. A threaded stem l5 extends from the upper end ofthe valve casing through a threaded opening in the cap l2, and to thisstem is connected a nut 16, by which the stem of the valve may be turnedto adjust the valve casing upwardly or downwardly with respect to thedrum. rfhe valve casing is provided with ports 17 and 17a whichcommunicate with the interior of the drum so that may flow from theopening 3 through the channel 8 and ports 9 into the drum and thencethrough the ports 17 and 17 a into the valve casing. 1Vithin the valvecasing is arranged a valve comprising a piston 18, adapted to open andclose ports 17 and a piston 19 adapted to open and close the ports 17a,these pistons being connected together by a rod or stem 20 on which theyare mounted. These pistons are formed with openings CZ through them topermit the which enters the casing to ilow through the pistons and intothe lower part of the casing below the partition 7, and from said lowerpart of the casing the gas may fiow through the outlet 4.

A bracket or support 21 extends downwardly from the lower wall 7 of thedrum and this bracket serves as a support for a system of levers whichactuate the valve 18-19. Thus, a lever 22 is pivoted to an ear 23 on thebracket and the longer arm of the lever is pivotally connected to thevalve stem 20. A link 23a connects the shorter arm of this lever withthe longer arm of a lever 24, the latter being pivoted upon a projection2.5 on the bracket and the shorter arm of the lever 24 is adapted torest upon a pin 2G which projects through an opening 27 in the lowerwall of the casing. This pin is slidable in a sight gage fitting 28,which is secured to the bottom ofthe casing, and the lower end of thepin is visible through the glass tube 29 of the gage. The pin isnormally pressed upward by a light spring 30 arranged between thefitting 28 and the head shown on the upper end of the pin. This springperforms no other function than to support the pin and keep it inconstant contact with the lever 24. Attached to the lower end of thesight gage is an expansion tube 31, which is adapted to eX- tend downinto the metal which is to be melted. rl`his tube contains in its lowerpart pieces of carbon 32, and a metal rod 33 rests upon the carbon andextends upwardly into the sight gage and abuts against the pin 26. Thepieces of carbon and the rod 33 are loosely held within the expansiontube and do not expand sufficiently with the heat to affect theoperation of the apparatus. The expansion tube 31 expands when heatedand this permits the carbon pieces and rod 33 to move downward and lowerthe pin 26. lVhen the expansion tubev becomes cool, it contracts andlifts the rod 33 and pin 26. The' details of the expansion tube are nota Vfeature of my invention.

n'Fig. 3 of the drawing, the valves ar shown in the position which theyoccupy when the expansionytube is cold. 1n this position, the rod 33 andpin 26 support the shorter arm of the lever 24C, and through the link23El and lever 22, the valves are supported above the ports 17 and 17a.ln this position of the valves, gas may pass freely through the inletport 3 to the chamber within the drum, and thence through the ports 17into the lower chamber below the drum, and thence outward through theoutlet opening l to the burners of the furnace. The expansion tube 31extends into the metal which is to be melted and, as the telnperaturerises, this tube expands downwardly, thereby permitting the rod 38 andpin 2G to descend, and the pistons 18 and 19 also are permitted todescend by gravity, thus gradually closing the ports 17, 17, and

whenY the metal is at the desired temperature, these pistons willentirely close the ports and cut off the flow of gas. The apparatus isadjusted so that when the pistons entirely close the ports 17, 17a, thedownward movement of the pin will be stopped by the engagement of itshead with the fitting 28 and the rod 33 will move away from the pin andthis separation of the rod and pin, which is visible through the gageglass, will indicate to the operator that the piston valves are in theirclosed positions and that the apparatus is working as intended. Byadjusting the valve casing 1li, by means of the nut 16, the positions ofthe ports with respect to the pistons may be adjusted so that the valveswill close sooner or later, according to the degree of heat which it isdesirable or necessary to apply to the metal. The ports (Z in thepistons are provided so that the pressures will be equaliZed on oppositesides of the pistons.

In order to maintain a small supply of gas to the burners to keep themlighted after the main supply has been cut off, I provide means forpassing a small iow of gas from i the chamber within the drum to thechainber below the drum, without passing through the ports 17, 17a.Thus, in the lower wall of the drum is shown a small opening 3st,through which the gas may pass, and a needle valve 35, extending throughthe upper wall of the drum, adapted to fit into this opening to closethe saine or to permit any desirable amount of gas to flow through. Asshown, the needle falve has a threaded portion 35 litting into athreaded opening in the top of the drum., and the valve may be locked inany -desired position of adjustment by means of a nut 36.

lWhat 1 claim is:

1. A thermostatic control device comprising an outer casing, closed atone end and open at the other end and having' upper and lower gasopenings, a drum removably secured within the upper part of said casingand communicating with one of said openings, a valve casing within thedrum and opening into the lower part of said outer casing, said valvecasing having a port within the drum, a piston valve, fitting within thevalve casing, for opening and closing said port, said valve having aport extending through it, a bracket depending from the lower wall ofthe drum, a system of movement multiplying levers supported by saidbracket and connected to the valve, and an expansion device for movingsaid levers.

2. A thermostatic control device comprising an outer casing, closed atone end and open at the other end and having upper and lower' gasopenings, a drum removably secured within the upper part of said casing'and cmmunicatingg,` with one of said openings, a valve casing extendingthrough the drum and slidably mounted in its upper and lower walls, saidvalve casing having a port within the drum, means for adjusting the saidvalve casing longitudinally, a piston valve iitting within the valvecasing, for opening and closing said port, said valve having a portextending through it, a system oit movement multiplying levers supportedby said drum and connected to the valve, and an expansion device formoving said levers.

3. A thermostatic control device comprising an outer casing, vclosed atone end and open at the other end and having upper and lower gasopenings, a drum removably secured within the upper part oi said casingand communicating with one of said openings, a valve casing within'thedrinn and opening into the lower part of said outer casing, said valvecasing having a port within the drum, a piston valve, fitting within thevalve casing, for opening and closing said port, said valve having aport extending through it, a bracket depending from the lower wall ofthe drum, a system of movement multiplying levers supported by saidbracket and conected to the valve, an expansion device for moving saidlevers, a port extending through the lower Wall of the drum, and amanually adjustable valve for varying the effective size of said latterport. 4. In a thermostatic control device, an outer casing, closed atits lower end and open at its upper end and having inlet and outletports arranged one above the other in its side wall, a drum fittingwithin and closing the open end of the casing, the lower wall of saiddrum forming a partition between said openings in the outer casing, saidwall having an opening, a valve carried by the drum for controlling thelow of gas through said latter opening', a system of multiplying leverscarried by the drum and connected to said valve, and an expansion deviceexternal to the casing and connected to the same for causing theactuation of the levers and valve.

In testimony whereof I hereunto aiix my signature.

CHARLES F. I-I. BOHNHARDT.

